The objective of this investigation is to grow homogeneous cultures of retinal vascular endothelium. Studies involving this cell may help us to understand such blinding diseases as diabetic retinopathy, which mainly affect the endothelial cell and pericyte. Bovine retinas will be homogenized to yield isolated capillary fragments. These will then be subjected to enzymatic digestion, producing a suspension of endothelial cells, pericytes, smooth muscle cells, and other retinal elements. After preliminary culturing of the cells to allow recovery from the harvesting procedure, endothelial cells in the mixed population will be selectively stained with antifactor VIII antibody. Then, using the technology of fluorescence activated cell sorting, the endothelial cells will be separated out. This homogenous population can be recultured, then studied morphologically and biochemically.